"Professionally ambitious women really only have two options when it comes to their personal partners — a super-supportive partner or no partner at all," Wittenberg-Cox writes. "Anything in between ends up being a morale- and career-sapping morass."

Although this toxic dynamic can occur within any relationship, Wittenburg-Cox says it overwhelmingly affects women in heterosexual marriages. Many husbands who start off encouraging their wives end up becoming resentful.

Too often, "women are left shocked and surprised," Wittenberg-Cox writes. They expect marriage to be a partnership where both spouses support each other and take turns in the limelight.

Unfortunately, many of their husbands don't agree. And "it's almost always the woman whose career comes second," she writes.

Wittenberg-Cox points to a survey of Harvard Business School graduates in which more than 50 percent of men said they expect their own career to come first. In the same study, the majority of women expected their marriages to be egalitarian.

Another study she cites found that when women choose to leave the workforce, most aren't doing so entirely of their own accord: 66 percent say their husbands were a critical factor in the decision. When parenting duties crop up, even many "supportive" husbands push the responsibilities onto their wives.

Money and the gender pay gap make the problem worse. "Men get more opportunities to earn more, and it gets harder and harder for women to catch up," Wittenberg-Cox writes. Instead, often, they drop out.

Their dreams, however, don't just disappear. Having to repress them can lead to tension and frustration and even divorce. In fact, Wittenberg-Cox points out, "about 60 percent of late-life divorces are initiated by women, often to focus their energies on flourishing careers post-50."

"You want to associate with people who are the kind of person you'd like to be. You'll move in that direction," Buffett said in a conversation with Bill Gates at Columbia University. "And the most important person by far in that respect is your spouse. I can't overemphasize how important that is."

Sandberg agrees. "I truly believe that the single most important career decision that a woman makes is whether she will have a life partner and who that partner is," she writes in her bestseller "Lean In."

"I don't know of one woman in a leadership position whose life partner is not fully — and I mean fully — supportive of her career."

"You can date whoever you want, but you should marry the nerds and the good guys," Sandberg once told an interviewer. "The guys who want an equal relationship. Guys who want to support your career."